Enhanced Adhesion Effect of Epoxy Resin on Metal Surfaces Using Polymer with Catechol and Epoxy Groups

Reinforcement of the interfacial interaction between epoxy adhesives and metallic materials was achieved by using poly(glycidyl methacrylate) (PGMA) with N-(3,4-dihydroxyphenethyl)methacrylamide (DOPAm) fragments. The copolymer, namely P(GMA-co-DOMAm), was synthesized via reversible addition–fragmentation chain-transfer polymerization. Because of the catechol anchoring, the polymeric layer was successfully prepared by immersing metals in the copolymer solution for 1 h. The single-lap shear test demonstrated that the ultimate lap shear strength of the adherent with the polymeric layer was almost twice stronger than the bare one when the epoxy resin was utilized as adhesives. The X-ray photoelectron spectroscopic measurement at the adherent/adhesive interface revealed that the catechol-anchoring effect, as well as the cross-linking between the polymer brush and adhesives dramatically improved the performance of epoxy adhesives.